The need for effective antiviral agents continues to exist, especially antiviral agents with an improved therapeutic ratio.
Unexpectedly, we have found that a group of peptides exhibit antiviral properties against herpes viruses with apparently no deleterious effects on the host subject.
The association of peptides with antiviral activity is unusual, but has been reported before. The subject peptides of the previous reports are distinguished from the present peptides by differences in their chemical structure and in their spectrum of activity. Instances of previous reports include: H. Umezawa et al., Canadian Pat. No. 1,098,850, Apr. 7, 1981; P. W. Choppin et al., J. Infect. Dis., 143, 352 (1981); and P. W. Choppin et al., in "Targets for the Design of Antiviral Agents", E. Declercq and R. T. Walker, eds., Plenum Press, New York, 1984, pp 287-305.
A noteworthy property of the peptides of this application is the enhancement of their antiviral activity when they are combined with a protease inhibitor, for example, the antibiotic bacitracin. In this context, it is interesting to note that bacitracin, when used alone, has been reported as being inactive against HSV-1 by A. Alarcon et al., Antiviral Research, 4, 231 (1984); and that bacitracin in combination with neomycin and glycyrrhizin has been proposed for treating oral infections, R. Segal et al., U.K. patent application No. 2167296, published May 29, 1986. Hence, the enhancement of the antiviral activity realized with the straight forward combination of the peptides and a protease inhibitor represents an unexpected turn of events.